Thermal printhead

ABSTRACT

The object of the invention is to enhance precision in bonding the heating board and the radiating plate of a thermal print head, in the thermal print head A composed by attaching the heating board  2  on the surface of which a heating resistor for printing  4  is formed on the upper surface of the radiating plate  1 , an identification mark M that functions as a positioning reference when the heating board  2  is attached on the radiating plate  1  is provided on the heating board  2  at a fixed interval from the heating resistor  4  and in addition, the identification mark M has a vertical side M 1  equivalent to a positioning reference line D perpendicular to a direction in which the heating resistor of the heating board  2  is arranged (the direction of the x-axis).

TECHNICAL FIELD

The present invention relates to a thermal print head composed of aheating board and a radiating plate, detailedly relates to a thermalprint head provided with an identification mark for positioning when aheating board is bonded to a radiating plate.

BACKGROUND ART

Heretofore, this type of thermal print head is composed by attaching aceramic heating board onto the upper surface of a metallic radiatingplate. A heating resistor for printing, a common electrode pattern andan individual electrode pattern are formed on the surface of the heatingboard and plural IC chips for driving are mounted. In case the heatingboard having the configuration described above is attached to theradiating plate, an adhesive and a pressure sensitive adhesive tape aregenerally used, however, in any case, precise positioning is requiredand particularly, to position precisely in the longitudinal direction ofthe heating board, that is, in the direction of the x-axis which is adirection in which the heating resistor is arranged, heretofore, a firstdot part (the leading end) and a last dot part (the trailing end) of theheating resistor linearly formed on the heating board are based.

That is, the first dot part and the last dot part of the heatingresistor are directly recognized as a binary number by a camera andothers, the heating board is precisely set on the radiating plate and isbonded based upon it.

However, recently, the demand of a thermal print head wherein a heatingresistor is covered with a conductive protective coat is increased and aproblem that precision in bonding between a heating board and aradiating plate decreases because such a conductive protective coat isformed occurs.

That is, as a heating resistor is generally black, while a conductiveprotective coat is also approximately black, it is difficult torecognize the first dot part and the last dot part of the heatingresistor by a camera and as a result, misregistration by wrongrecognition occurs.

Therefore, it is considered that an identification mark different from aheating resistor is required and is based, however, wrong recognition iscaused depending upon the shape of a mark and satisfactory bondingprecision is not achieved. The object of the invention is to provide athermal print head wherein an identification mark for positioningenabling solving such problems is provided.

DISCLOSURE OF THE INVENTION

To solve the problems, a first aspect of the invention is based upon athermal print head wherein a heating board on the surface of which aheating resistor for printing is formed is attached on the upper surfaceof a radiating plate and is characterized in that the heating board isprovided with an identification mark having the vertical side for anorientation arranged perpendicularly to a direction in which heatingresistor is arranged so that the identification mark functions as theorientation when the heating board is attached to the radiating plate.

Therefore, as a first dot part and a last dot part of the heatingresistor can be more definitely recognized than they are directlyrecognized as a binary number by a camera, positioning when the heatingboard is attached to the radiating plate can be precisely performed.Particularly, even if the identification mark is formed using gold foiland others which is hardly recognized when the parts are recognized as abinary number, a longitudinal reference line formed by the vertical sidedefinitely appears and wrong recognition can be possibly prevented.

Also, a second aspect of the invention is based upon the thermal printhead according to the first aspect of the invention and is characterizedin that the heating resistor is covered with a protective coat. That is,as positioning can be precisely performed even if it is difficult torecognize the heating resistor as a binary number by a camera because ofthe protective coat, positional precision for attaching the heatingboard onto the radiating plate can be enhanced.

Also, a third aspect of the invention is based upon the thermal printhead according to the first aspect of the invention and is characterizedthe identification mark is provided in a position except the protectivecoat.

Therefore, even if the identification mark is formed in approximatelythe same color as that of the protective coat, a precise positionalreference can be acquired.

Also, a fourth aspect of the invention is based upon the thermal printhead according to the first aspect of the invention and is characterizedin that as for the identification mark, the vertical side is provided inonly one location. Therefore, there is no possibility that anothervertical side is recognized as a reference position by mistake.

A fifth aspect of the invention is based upon the thermal print headaccording to any of the first to third aspects of the invention and ischaracterized in that the identification mark is composed of an Xreference line formed by the vertical side and a Y reference line formedby the side perpendicular to the vertical side.

According to such configuration, alignment not only in the longitudinaldirection (the direction of X) but in the direction of Y can be achievedand extremely precise alignment is enabled.

A sixth aspect of the invention is based upon the thermal print headaccording to the first aspect of the invention and is characterized inthat the identification mark is made of a thick film printed pattern.

A seventh aspect of the invention is based upon the thermal print headaccording to the first aspect of the invention and is characterized inthat the identification mark is made of a thin film pattern.

An eighth aspect of the invention is based upon the thermal print headaccording to the sixth or seventh aspect of the invention and ischaracterized in that the identification mark is formed in a process forforming an electrode pattern. According to such configuration, theidentification mark can be formed at the same time that the electrodepattern is formed without requiring another process and further, asrelative positioning is applied to the electrode pattern by a mask,extremely precise positioning is enabled.

Also, a ninth aspect of the invention is based upon the thermal printhead according to any of the first to the third aspects of the inventionand is characterized in that the identification mark is a polygon havingthe vertical side as one side. Therefore, in case the polygon isrecognized as a binary number, the plane is clearly shown and thevertical side to be a reference can be definitely recognized. Also, forexample, in the case of a polygon having the side perpendicular to thevertical side, positioning not only in the longitudinal direction of theheating board but in the direction of the width can be preciselyperformed.

Further, a tenth aspect of the invention is based upon the thermal printhead according to any of the first to third aspects of the invention andis characterized in that the identification mark is a semicircle havingthe vertical side as one side. Therefore, the area of the mark toacquire precise recognition can be reduced up to the required minimumlimit, the quantity of pasted gold, aluminum and others for forming themark can be reduced and the cost can be reduced.

An eleventh aspect of the invention is based upon a method of mountingthe heating board on the surface of which the heating resistor forprinting is formed on the radiating plate and forming the thermal printhead and is characterized in that a process for forming the heatingboard on which the heating resistor for printing, the identificationmark having the vertical side perpendicular to a direction in which theheating resistor is arranged and the electrode pattern connected to theheating resistor are formed and a process for aligning and fixing theheating board on the radiating plate using the vertical side of theidentification mark as a positioning reference line are included.Therefore, as the first dot part and the last dot part of the heatingresistor can be more definitely recognized than they are directlyrecognized as a binary number by a camera, positioning when the heatingboard is attached on the radiating plate can be precisely performed.Particularly a longitudinal reference line formed by the vertical sideto be a reference is definitely shown and wrong recognition can bepossibly prevented.

A twelfth aspect of the invention is based upon the method ofmanufacturing the thermal print head according to the eleventh aspect ofthe invention and is characterized in that the identification mark isformed in the process for forming the electrode pattern. According tosuch a method, the identification mark can be easily formed withoutrequiring another process.

A thirteenth aspect of the invention is based upon the method ofmanufacturing the thermal print head according to the eleventh aspect ofthe invention and is characterized in that the identification mark iscomposed of an X reference line formed by the vertical side and a Yreference line formed by the side perpendicular to the vertical side.

A fourteenth aspect of the invention is based upon the method ofmanufacturing the thermal print head according to the eleventh aspect ofthe invention and is characterized in that the process for forming theidentification mark is equivalent to the process for forming theelectrode pattern. According to such configuration, alignment not onlyin the longitudinal direction (the direction of X) but in the directionof Y can be achieved and extremely precise alignment is enabled.

A fifteenth aspect of the invention is based upon the method ofmanufacturing the thermal print head according to the fourteenth aspectof the invention and is characterized in that the process for formingthe identification mark includes a thick film printing process.

A sixteenth aspect of the invention is based upon the method ofmanufacturing the thermal print head according to the fourteenth aspectof the invention and is characterized in that the process for formingthe identification mark includes the thick film printing process forprinting on the whole surface and a pattern forming process forpatterning it by photolithography.

A seventeenth aspect of the invention is based upon the method ofmanufacturing the thermal print head according to the fourteenth aspectof the invention and is characterized in that the process for formingthe identification mark includes a thin film forming process and thepattern forming process for patterning it by photolithography.

The invention is based upon a thermal print head wherein a heating boardon the surface of which a heating resistor for printing is formed isattached on the upper surface of a radiating plate and is characterizedin that an identification mark which functions as a positioningreference when a heating board is attached on a radiating plate isprovided on the heating board at a fixed interval from a heatingresistor and in addition, the identification mark has the vertical sideequivalent to a positioning reference line in the direction of thex-axis equivalent to the longitudinal direction of the heating board.

That is, the first dot part and the last dot part of the heatingresistor can be more definitely recognized by providing theidentification mark for positioning on the heating board than they aredirectly recognized as a binary number by a camera as heretofore,positioning when the heating board is attached on the radiating platecan be precisely performed and attaching precision can be enhanced.

The identification mark can be easily formed by printing and gold,aluminum and others are suitably used for paste for printing.

Particularly as for gold, in case it is binarized when it is monitoredby a television camera, it is often judged blank, however, in the caseof the shape described above, as a longitudinal reference line formed bythe vertical side to be a reference is definitely shown, gold paste maybe used.

The heating resistor of a thermal print head is often covered with aconductive protective coat and in the case of such a thermal print headthe heating resistor of which is covered with a conductive protectivecoat and in addition, in case the color of the heating resistor isapproximately the same color as that of the protective coat, it isdifficult to directly recognize the first dot part and the last dot partof the heating resistor as a binary number by a monitor as describedabove, however, positioning can be precisely performed by providing theidentification mark at a fixed interval from the heating resistor.

Such an identification mark can be also formed on the conductiveprotective coat, however, even if the identification mark is formed inapproximately the same color as that of the protective coat, a precisepositional reference can be acquired by providing the identificationmark in a position in which no protective coat is provided

The identification mark can be in a shape such as the vertical side isprovided in only one location. The reason is that when plural verticallines to be a reference are provided, they are misleading and othervertical lines are easily wrongly recognized as a reference position.

Also, the identification mark may be also a polygon and a semicircleeach one side of which is a vertical side.

As these shapes are familiar and a plane is clearly shown in case theyare binarized, the vertical side to be a reference can be definitelyrecognized.

Particularly, in the case of a polygon having the side perpendicular tothe vertical side, positioning not only in the longitudinal direction ofthe heating board but in the direction of the width can be preciselyperformed.

Further, in the case of a triangle, paste such as gold and aluminum forforming the identification mark is saved and the cost can be reduced.

To reduce the quantity of paste, as the area can be minimized in thecase of a semicircle, it is more effective to reduce the cost.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan showing a thermal print head equivalent to anembodiment;

FIG. 2 is an exploded perspective view showing the thermal print head;

FIG. 3 is an explanatory drawing showing an embodiment of anidentification mark;

FIG. 4 is an explanatory drawing showing another embodiment of theidentification mark;

FIG. 5 is an explanatory drawing showing further another embodiment ofthe identification mark;

FIGS. 6(a) through 6(c) are explanatory drawings showing further anotherembodiment of the identification mark;

FIG. 7 is an explanatory drawing showing further another embodiment ofthe identification mark; and

FIGS. 8(a) through 8(f) are explanatory drawings showing the otherembodiment of the identification mark.

BEST MODE FOR CARRYING OUT THE INVENTION

Referring to the drawings, an embodiment of the invention will bedescribed in detail below.

FIG. 1 is a plan showing a thermal print head A equivalent to thisembodiment and FIG. 2 is an exploded perspective view showing thethermal print head A.

As shown in these drawings, the thermal print head A is characterized inthat a ceramic heating board 2 and a printed circuit board 3 made ofsynthetic resin are aligned and fixed on the upper surface of aradiation plate 1 made of metal such as aluminum using an alignment markM having a positioning reference line perpendicular to the longitudinaldirection of the heating board 2. The alignment mark M is formed in aprocess for forming a common electrode pattern 6 or an individualelectrode pattern 7.

The upper surface of the radiating plate 1 is composed of upper andlower planes for mounting the boards 11 and 12 as shown in FIG. 2, theheating board 2 is mounted on the higher plane 11 and the printedcircuit board 3 is mounted on the lower plane 12. In this embodiment,the boards are bonded using a UV adhesive. In FIG. 2, the commonelectrode pattern 6, the individual electrode pattern 7 and IC fordriving 5 are omitted.

The heating resistor for printing 4 is formed near one side in thelongitudinal direction of the surface of the heating board 2 on theheating board 2 with the resistor linearly extended and plural IC chipsfor driving 5 are arranged in a row near a side opposite to the sidedescribed above. The heating resistor 4 made of ruthenium oxide (RuO₂)and formed linearly by thick film printing, the common electrode pattern6 and the individual electrode pattern 7 are formed on the heating board2. These common electrode pattern 6 and individual electrode pattern 7are made of a gold thick film pattern formed alternately like a comb sothat they are opposite from a direction perpendicular to the heatingresistor under the heating resistor. The other end of the individualelectrode pattern 7 is connected to the IC chip for driving 5. Also, thecommon electrode pattern 6 is composed of the side extended in thelongitudinal direction of the heating board 2, an extended part extendedalong a shorter side on both sides of the side and connected to theprinted circuit board 3 and a comb-type electrode part forming the teethof a comb vertically extended from the side to the heating resistor 4and the comb-type electrode part is connected to the heating resistor.The extended part is connected to the printed circuit board 3 via aterminal electrode 8 and a terminal lead 9 provided at both ends of theprinted circuit board 3. The heating resistor 4 is covered with aconductive protective coat 41 having predetermined width. The conductiveprotective coat 41 is formed to prevent destruction by staticelectricity. The common electrode pattern and the individual electrodepattern are formed by patterning a gold film formed on the whole surfaceof the board by thick film printing using photolithography and thealignment mark M can be easily formed only by changing a mask used forthe photolithography without requiring a special process. Also, it isdesirable that the alignment mark has a vertical side M1 perpendicularto the longitudinal direction in which a minute and high-precisionpattern can be formed because the alignment mark is formed byphotolithography and a parallel side M2 perpendicular to the verticalside, a position in the longitudinal direction, that is, the directionof the x-axis and in the direction of the y-axis perpendicular to thedirection of the x-axis is precisely defined and precise alignment isenabled by positioning based upon the alignment mark.

Each terminal electrode 8 connected to each IC chip for driving 5 via awiring pattern not shown is formed at both ends of a longer side of theIC chip for driving 5, and each terminal electrode 8 and a connectingelectrode 31 formed at right and left ends on the upper surface of theprinted circuit board 3 are connected via the terminal lead 9.

Further, bonding wire not shown connects each individual electrodepattern 7 and the IC chip for driving 5 and connects the IC chip fordriving 5 and each wiring pattern not shown, and the IC chip for driving5 and the bonding wire are covered with a protective coat 51 made ofsynthetic resin.

As for the printed circuit board 3, a connector connection 32 is formedapproximately in the center of the longer side of the printed circuitboard, and a wiring circuit pattern not shown for connecting a connectorC connected to the connector connection 32 for connecting an externaldevice and the connecting electrode 31 is formed on the surface of theboard.

A reference number 21 shown in FIG. 1 denotes a thermistor arrangedbetween the rows of the IC chip for driving 5 as a thermostatic elementand Cl denotes a contact pin of the connector C for connecting anexternal device.

When the thermal print head A is manufactured, a process for bonding theheating board 2 to the radiating plate 1 is required, however, in thatcase, first, the heating board 2 and the printed circuit board 3 arecoupled via the terminal lead 9 and both are simultaneously bonded onthe radiating plate 1. At this time, when the heating board 2 and theprinted circuit board 3 are coupled and when both are bonded on theradiating plate 1, the heating board 2 is required to be preciselypositioned using the alignment mark M and is required to be preciselylaid on the surface to be mounted.

According to the invention, extremely precise positioning is enabled,compared with a conventional method of catching the heating board 2 by apair of tweezers and others, driving an XY table, positioning andsetting the heating board, recognizing any mark on the heating board 2,the first dot part and the last dot part as a mark of the heatingresistor 4 as a binary number by a camera not shown. As described above,the invention is characterized in that the identification mark M thatfunctions as a positioning reference in positioning is provided at afixed interval from the heating resistor 4 on the heating board 2 and inaddition, the identification mark M has a vertical side M1 equivalent toa positioning reference line D in the direction of the x-axis equivalentto the longitudinal direction of the heating board 2.

In this embodiment, as shown in FIG. 1, the identification mark M isrespectively formed by gold paste by printing at a predeterminedinterval on the side of the IC chip for driving respectively from aleading end equivalent to the first dot part of the heating resistor 4and from a trailing end equivalent to the last dot part, and inaddition, each identification mark M is in the shape of a rightisosceles triangle composed of the vertical side M1 equivalent to thepositioning reference line D, a horizontal side M2 perpendicular to thevertical side and having the same length as the vertical side and ahypotenuse M3 in this embodiment (see FIG. 3).

As described above, a reference can be more definitely recognized byproviding the identification mark M for positioning than the first dotpart and the last dot part of the heating resistor 4 are directlyrecognized as a binary number by a camera as heretofore and positioningwhen the heating board 2 is attached on the radiating plate 1 can beprecisely performed.

In addition, as the heating resistor 4 is not directly recognized butthe identification mark is provided in a position apart from the heatingresistor even if the heating resistor 4 is covered with the conductiveprotective coat 41 as in this embodiment, precise positioning is enabledindependent of whether the conductive protective coat 41 is provided ornot and attaching positional precision can be enhanced.

Also, as the mark is in the shape of not a dot and a line but a planefigure, the vertical side M1 to be a reference line is definitely shownlongitudinally. Therefore, even if the identification mark M is formedusing gold paste often judged blank when binarized as in thisembodiment, wrong recognition can be prevented.

Further, paste for forming the mark having the same color as that of theconductive protective coat 41 can be used by forming the identificationmark M in a position apart from the conductive protective coat 41 asshown in FIG. 1 and the degree of freedom in selecting paste isincreased.

Also, in this embodiment, as the vertical side M1 of the identificationmark M is provided in only one location, no other vertical lines thatmay be recognized as a reference position by mistake exist, the verticalside can be precisely recognized and attaching positional precision canbe more enhanced. Further, in this embodiment, as the horizontal side M2perpendicular to the vertical side M1 is provided, positioning both inthe longitudinal direction of the heating board 2 and in the directionof the width can be precisely performed.

In addition, the area of the identification mark M can be possiblyreduced by providing a triangular mark, gold paste is saved and the costcan be reduced.

Any identification mark M having the vertical side M1 equivalent to thepositioning reference line D is included in the invention and thepresent invention is not limited to the identification marks describedabove. For example, the identification mark M may be also in the shapeof an equilateral triangle having the vertical side as a base as shownin FIG. 4.

Also, the identification mark may be also a square shown in FIG. 5 or arectangle for example without limiting to the triangle. However, inthese cases, as a border line M4 equivalent to the vertical side M1shown in FIG. 3 appears in parallel, it may be difficult to discriminatewhich vertical line is to be a reference.

Further, the identification mark M may be also not only the triangle andthe quadrangle but another polygon and for example, shapes shown inFIGS. 6(a) to 6(c) are conceivable.

The identification mark M is not a polygon but may be also a semicirclehaving the vertical side M1 as one side as shown in FIG. 7. In thiscase, the area of the identification mark M can be reduced up to arequired minimum limit and the cost can be most reduced because thequantity of paste for forming the mark is saved.

Furthermore, the identification mark M may be also in various shapeexcept the shapes described above, for example shown in FIGS. 8(a) to8(f). Any shape shown in FIGS. 3 to 8 except FIG. 5 has the verticalside M1 in only one location.

Needless to say, as for the shape of the identification mark M, furthervarious shapes are conceivable in a range of the object of theinvention. Also, a position in which the identification mark M is formedis also not limited to the embodiment, may be suitably determined andfor example, may be also on the conductive protective coat 41.

Also, in the embodiment, the electrode pattern is formed by thick filmprinting and photolithography, however, a printing pattern using a maskscreen having an electrode pattern and a pattern of an alignment markmay be also used.

Furthermore, an electrode pattern can be also formed by patterning athin film pattern formed by a method such as vacuum deposition andsputtering by photolithography.

Also, in the embodiment, the heating resistor is composed of anintegrated pattern formed linearly and for the electrode, the comb-typeelectrode is used, however, it need scarcely be said that the inventioncan be also applied to a case that the heating resistor is formed by anindividual pattern. Furthermore, the alignment mark is not necessarilyrequired to be formed in the electrode pattern forming process and maybe also formed in another process.

INDUSTRIAL APPLICABILITY

According to the invention, in the thermal print head composed byattaching the heating board on the surface of which the heating resistorfor printing is formed on the upper surface of the radiating plate, theidentification mark to be a positioning reference when the heating boardis attached on the radiating plate is provided at a fixed interval fromthe heating resistor on the heating board, in addition, the longitudinalreference line formed by the vertical side to be reference is definitelyshown by providing a vertical side equivalent to a positioning referenceline in the direction of the x-axis equivalent to the longitudinaldirection of the heating board to the identification mark and wrongrecognition can be possibly prevented, and positioning when the heatingboard is attached on the radiating plate can be precisely performed.

According to the invention, in the thermal print head, even if theheating resistor is covered with the protective coat, positionalprecision in attaching the heating board on the radiating plate can beenhanced as in the case described above.

According to the invention, as the identification mark is provided in aposition apart from the protective coat, a precise positional referencecan be acquired even if the identification mark is formed inapproximately the same color as that of the protective coat and thedegree of freedom in selecting the type of paste for forming the mark isincreased.

According to the invention, as the identification mark has the verticalside in only one location, no other vertical sides are recognized as areference position by mistake.

According to the invention, as the identification mark is a polygonhaving a vertical side as one side, a plane is clearly shown whenbinarized and the vertical side to be a reference can be definitelyrecognized. Also, in case the identification mark is a polygon having abottom perpendicular to the vertical side, positioning not only in thelongitudinal direction of the heating board but in the direction of thewidth can be precisely performed.

According to the invention, as the identification mark is a semicirclehaving a vertical side as one side, the area of the mark for acquiringprecise recognition can be reduced up to a required minimum limit, thequantity of paste such as gold and aluminum for forming the mark can bereduced and the cost can be reduced.

What is claimed is:
 1. A thermal print head comprising a heating boardon the surface of which a heating resistor for printing is formed, theheating board being mounted on a radiating plate, wherein: said heatingboard is provided with an identification mark having a vertical side fora positioning reference arranged perpendicularly to a direction in whichsaid heating resistor is arranged so that the identification mark is apositioning reference when the heating board is attached on saidradiating plate; and wherein said heating resistor is covered with aprotective coat that is approximately black.
 2. A thermal print headaccording to claim 1, wherein: said identification mark is arranged at apredetermined interval from said heating resistor.
 3. A thermal printhead according to claim 1, wherein: said identification mark has avertical side in only one location.
 4. A thermal print head according toclaim 1, wherein: said identification mark is composed of an X referenceline formed by a vertical side and a Y reference line formed by a sideperpendicular to the vertical side.
 5. A thermal print head according toclaim 1, wherein: said identification mark is a thick film printedpattern.
 6. A thermal print head according to claim 5, wherein: saididentification mark is formed in a process for forming an electrodepattern.
 7. A thermal print head according to claim 1, wherein: saididentification mark is a thin film pattern.
 8. A thermal print headaccording to claim 1, wherein: said identification mark is a polygonhaving a vertical side as one side.
 9. A thermal print head according toclaim 1, wherein: said identification mark is a semicircle having avertical side as one side.
 10. A method of mounting a heating board onthe surface of which a heating resistor for printing is formed on aradiating plate and forming a thermal print head, comprising: a processfor forming a heating board on which a heating resistor for printing, anidentification mark having a vertical side perpendicular to a directionin which the heating resistor is arranged and an electrode patternconnected to said heating resistor are formed; a process for coveringthe heating resistor with a protective coating that is approximatelyblack; and a process for aligning the heating board on said radiatingplate using said vertical side of said identification mark as apositioning reference line and fixing said heating board.
 11. A methodof manufacturing the thermal print head according to claim 10, wherein:said identification mark is formed in a process for forming saidelectrode pattern.
 12. A method of manufacturing the thermal print headaccording to claim 10, wherein: said identification mark is composed ofan X reference line formed by a vertical side and a Y reference lineformed by a side perpendicular to the vertical side.
 13. A method ofmanufacturing the thermal print head according to claim 10, wherein: aprocess for forming the identification mark is the same process as theprocess for forming the electrode pattern.
 14. A method of manufacturingthe thermal print head according to claim 13, wherein: the process forforming the identification mark includes a thick film printing process.15. A method of manufacturing the thermal print head according to claim13, wherein: the process for forming the identification mark includesthe thick film printing process for printing on the whole surface and apattern forming process for patterning the thick film byphotolithography.
 16. A method of manufacturing the thermal print headaccording to claim 13, wherein: the process for forming theidentification mark includes a thin film forming process and a patternforming process for patterning the thin film by photolithography.